Computer Science & Mathematics
http://www.mdpi.com/journal/computer-math
Latest open access articles published in Computer Science & Mathematics at http://www.mdpi.com/journal/computer-math<![CDATA[Technologies, Vol. 3, Pages 19-36: Characterization of a Large, Low-Cost 3D Scanner]]>
http://www.mdpi.com/2227-7080/3/1/19
Imagery-based 3D scanning can be performed by scanners with multiple form factors, ranging from small and inexpensive scanners requiring manual movement around a stationary object to large freestanding (nearly) instantaneous units. Small mobile units are problematic for use in scanning living creatures, which may be unwilling or unable to (or for the very young and animals, unaware of the need to) hold a fixed position for an extended period of time. Alternately, very high cost scanners that can capture a complete scan within a few seconds are available, but they are cost prohibitive for some applications. This paper seeks to assess the performance of a large, low-cost 3D scanner, presented in prior work, which is able to concurrently capture imagery from all around an object. It provides the capabilities of the large, freestanding units at a price point akin to the smaller, mobile ones. This allows access to 3D scanning technology (particularly for applications requiring instantaneous imaging) at a lower cost. Problematically, prior analysis of the scanner’s performance was extremely limited. This paper characterizes the efficacy of the scanner for scanning both inanimate objects and humans. Given the importance of lighting to visible light scanning systems, the scanner’s performance under multiple lighting configurations is evaluated, characterizing its sensitivity to lighting design.Technologies2015-01-3031Article10.3390/technologies301001919362227-70802015-01-30doi: 10.3390/technologies3010019Jeremy StraubBenjamin KadingAtif MohammadScott Kerlin<![CDATA[Electronics, Vol. 4, Pages 118-149: Roll and Bank Estimation Using GPS/INS and Suspension Deflections]]>
http://www.mdpi.com/2079-9292/4/1/118
This article presents a method that provides an estimate of road bank by decoupling the vehicle roll due to the dynamics and the roll due to the road bank. Suspension deflection measurements were used to provide a measurement of the relative roll between the vehicle body frame and the axle frame or between the sprung mass and the unsprung mass, respectively. A deflection scaling parameter was found via suspension geometry and dynamic analysis. The relative roll measurement was then incorporated into two different kinematic navigation models based on extended Kalman filter (EKF) architectures. Each algorithm was tested and then verified on the Prowler ATV experimental platform at the National Center for Asphalt Technology (NCAT). Experimental data showed that both the cascaded and coupled approach performed well in providing estimates of the current vehicle roll and instantaneous road bank.Electronics2015-01-2941Article10.3390/electronics40101181181492079-92922015-01-29doi: 10.3390/electronics4010118Lowell BrownDavid Bevly<![CDATA[Econometrics, Vol. 3, Pages 65-90: Finding Starting-Values for the Estimation of Vector STAR Models]]>
http://www.mdpi.com/2225-1146/3/1/65
This paper focuses on finding starting-values for the estimation of Vector STAR models. Based on a Monte Carlo study, different procedures are evaluated. Their performance is assessed with respect to model fit and computational effort. I employ (i) grid search algorithms and (ii) heuristic optimization procedures, namely differential evolution, threshold accepting, and simulated annealing. In the equation-by-equation starting-value search approach the procedures achieve equally good results. Unless the errors are cross-correlated, equation-by-equation search followed by a derivative-based algorithm can handle such an optimization problem sufficiently well. This result holds also for higher-dimensional Vector STAR models with a slight edge for heuristic methods. For more complex Vector STAR models which require a multivariate search approach, simulated annealing and differential evolution outperform threshold accepting and the grid search.Econometrics2015-01-2931Article10.3390/econometrics301006565902225-11462015-01-29doi: 10.3390/econometrics3010065Frauke Schleer<![CDATA[Econometrics, Vol. 3, Pages 55-64: On the Interpretation of Instrumental Variables in the Presence of Specification Errors]]>
http://www.mdpi.com/2225-1146/3/1/55
The method of instrumental variables (IV) and the generalized method of moments (GMM), and their applications to the estimation of errors-in-variables and simultaneous equations models in econometrics, require data on a sufficient number of instrumental variables that are both exogenous and relevant. We argue that, in general, such instruments (weak or strong) cannot exist.Econometrics2015-01-2931Article10.3390/econometrics301005555642225-11462015-01-29doi: 10.3390/econometrics3010055P.A.V.B. SwamyGeorge TavlasStephen Hall<![CDATA[Economies, Vol. 3, Pages 2-36: Does a Least-Preferred Candidate Win a Seat? A Comparison of Three Electoral Systems]]>
http://www.mdpi.com/2227-7099/3/1/2
In this paper, the differences between two variations of proportional representation (PR), open-list PR and closed-list PR, are analyzed in terms of their ability to accurately reflect voter preference. The single nontransferable vote (SNTV) is also included in the comparison as a benchmark. We construct a model of voting equilibria with a candidate who is least preferred by voters in the sense that replacing the least-preferred candidate in the set of winners with any loser is Pareto improving, and our focus is on whether the least-preferred candidate wins under each electoral system. We demonstrate that the least-preferred candidate never wins under the SNTV, but can win under open-list PR, although this is less likely than winning under closed-list PR.Economies2015-01-2831Article10.3390/economies30100022362227-70992015-01-28doi: 10.3390/economies3010002Yoichi Hizen<![CDATA[Symmetry, Vol. 7, Pages 105-124: Two-Round Password-Only Authenticated Key Exchange in the Three-Party Setting]]>
http://www.mdpi.com/2073-8994/7/1/105
We present the first provably-secure three-party password-only authenticated key exchange (PAKE) protocol that can run in only two communication rounds. Our protocol is generic in the sense that it can be constructed from any two-party PAKE protocol. The protocol is proven secure in a variant of the widely-accepted model of Bellare, Pointcheval and Rogaway (2000) without any idealized assumptions on the cryptographic primitives used. We also investigate the security of the two-round, three-party PAKE protocol of Wang, Hu and Li (2010) and demonstrate that this protocol cannot achieve implicit key authentication in the presence of an active adversary.Symmetry2015-01-2771Article10.3390/sym70101051051242073-89942015-01-27doi: 10.3390/sym7010105Junghyun NamKim-Kwang ChooSangchul HanJuryon PaikDongho Won<![CDATA[Systems, Vol. 3, Pages 6-26: How Corporations Deal with Reporting Sustainability: Assessment Using the Multicriteria Logistic Biplot Approach]]>
http://www.mdpi.com/2079-8954/3/1/6
This paper suggests a new methodology capable of accessing in detail the contribution of companies to countries’ sustainability related to economic performance. The concept of sustainability has been brought up in several debates, leading to a clearer understanding of its progress in recent decades. The most adequate indicators to achieve a unique value to define sustainability have been identified. However, specific behaviors of economic agents such as exist in particularly large organizations, have rarely been exposed and evaluated regarding their positive or negative contribution to the increase of sustainability throughout the world. This paper proposes an integrated approach incorporating an evaluation of the positive and negative contributions to sustainability by means of a logistic biplot application. This allows the creation of a summarized index that combines all single sustainability indicators. These synthetic indices allow the positioning of each of the companies in a geometric representation for an original exploration of the sustainability paradigm. The supplied method permits accessing and evaluating information concerning specific behaviors of economic agents such as big companies. In our paper, we have followed the engagements towards sustainability of big corporations, individually or as groups, across the different activity sectors in Portugal and Spain.Systems2015-01-2731Article10.3390/systems30100066262079-89542015-01-27doi: 10.3390/systems3010006Purificación Vicente GalindoEric VazTeresa de Noronha<![CDATA[Information, Vol. 6, Pages 23-48: Measures of Information]]>
http://www.mdpi.com/2078-2489/6/1/23
This paper builds an integrated framework of measures of information based on the Model for Information (MfI) developed by the author. Since truth is expressed using information, an analysis of truth depends on the nature of information and its limitations. These limitations include those implied by the geometry of information and those implied by the relativity of information. This paper proposes an approach to truth and truthlikeness that takes these limitations into account by incorporating measures of the quality of information. Another measure of information is the amount of information. This has played a role in two important theoretical difficulties—the Bar-Hillel Carnap paradox and the “scandal of deduction”. This paper further provides an analysis of the amount of information, based on MfI, and shows how the MfI approach can resolve these difficulties.Information2015-01-2761Article10.3390/info601002323482078-24892015-01-27doi: 10.3390/info6010023Paul Walton<![CDATA[IJGI, Vol. 4, Pages 185-198: Conceptual Issues Regarding the Development of Underground Railway Laser Scanning Systems]]>
http://www.mdpi.com/2220-9964/4/1/185
Mobile Laser Scanning (MLS) systems are widely applied for spatial data collection and support applications in many aspects. In recent years, MLS technology had been introduced to railway applications and greatly enhanced the spatial detail and efficiency when compared to traditional approaches. However, the advance of MLS technology is not completely applied to railway environment. Typical MLS systems rely on integrated navigation through the use of Inertial Navigation Systems (INS) and Global Navigation Satellite Systems (GNSS) for geo-referencing, while operation under long-term GNSS outages or even GNSS-free environments, such as underground railway or long tunnels, remains a challenging issue due to the degraded operation of standalone inertial navigation. Commercial MLS systems usually employ high performance inertial measurement units (IMU) and various strategies to manage GNSS outages, but GNSS components are still necessary prior to and after experiencing the loss of GNSS signals. To tackle the problem of permanent GNSS outages, alternative methods are introduced to replace the GNSS and so allow the use of MLS systems in GNSS-free underground railway environments. Such approaches encourage the MLS systems to be developed into the Underground Railway Laser Scanning (URLS) systems, which may provide several alternative operational functions for the management of underground railway operation.ISPRS International Journal of Geo-Information2015-01-2741Article10.3390/ijgi40101851851982220-99642015-01-27doi: 10.3390/ijgi4010185Raymond HungBruce KingWu Chen<![CDATA[IJGI, Vol. 4, Pages 172-184: Remote Sensing Image Fusion at the Segment Level Using a Spatially-Weighted Approach: Applications for Land Cover Spectral Analysis and Mapping]]>
http://www.mdpi.com/2220-9964/4/1/172
Segment-level image fusion involves segmenting a higher spatial resolution (HSR) image to derive boundaries of land cover objects, and then extracting additional descriptors of image segments (polygons) from a lower spatial resolution (LSR) image. In past research, an unweighted segment-level fusion (USF) approach, which extracts information from a resampled LSR image, resulted in more accurate land cover classification than the use of HSR imagery alone. However, simply fusing the LSR image with segment polygons may lead to significant errors due to the high level of noise in pixels along the segment boundaries (i.e., pixels containing multiple land cover types). To mitigate this, a spatially-weighted segment-level fusion (SWSF) method was proposed for extracting descriptors (mean spectral values) of segments from LSR images. SWSF reduces the weights of LSR pixels located on or near segment boundaries to reduce errors in the fusion process. Compared to the USF approach, SWSF extracted more accurate spectral properties of land cover objects when the ratio of the LSR image resolution to the HSR image resolution was greater than 2:1, and SWSF was also shown to increase classification accuracy. SWSF can be used to fuse any type of imagery at the segment level since it is insensitive to spectral differences between the LSR and HSR images (e.g., different spectral ranges of the images or different image acquisition dates).ISPRS International Journal of Geo-Information2015-01-2641Article10.3390/ijgi40101721721842220-99642015-01-26doi: 10.3390/ijgi4010172Brian Johnson<![CDATA[JRFM, Vol. 8, Pages 43-82: Implied and Local Volatility Surfaces for South African Index and Foreign Exchange Options]]>
http://www.mdpi.com/1911-8074/8/1/43
Certain exotic options cannot be valued using closed-form solutions or even by numerical methods assuming constant volatility. Many exotics are priced in a local volatility framework. Pricing under local volatility has become a field of extensive research in finance, and various models are proposed in order to overcome the shortcomings of the Black-Scholes model that assumes a constant volatility. The Johannesburg Stock Exchange (JSE) lists exotic options on its Can-Do platform. Most exotic options listed on the JSE’s derivative exchanges are valued by local volatility models. These models needs a local volatility surface. Dupire derived a mapping from implied volatilities to local volatilities. The JSE uses this mapping in generating the relevant local volatility surfaces and further uses Monte Carlo and Finite Difference methods when pricing exotic options. In this document we discuss various practical issues that influence the successful construction of implied and local volatility surfaces such that pricing engines can be implemented successfully. We focus on arbitrage-free conditions and the choice of calibrating functionals. We illustrate our methodologies by studying the implied and local volatility surfaces of South African equity index and foreign exchange options.Journal of Risk and Financial Management2015-01-2681Article10.3390/jrfm801004343821911-80742015-01-26doi: 10.3390/jrfm8010043Antonie KotzéRudolf OosthuizenEdson Pindza<![CDATA[JRFM, Vol. 8, Pages 17-42: Pricing a Collateralized Derivative Trade with a Funding Value Adjustment]]>
http://www.mdpi.com/1911-8074/8/1/17
The 2008 credit crisis changed the manner in which derivative trades are conducted. One of these changes is the posting of collateral in a trade to mitigate the counterparty credit risk. Another is the realization that banks are not risk-free and, as a result, cannot borrow at the risk-free rate any longer. The latter led banks to introduced the controversial adjustment to derivative prices, known as a funding value adjustment (FVA), which is interlinked with the posting of collateral. In this paper, we extend the Cox, Ross and Rubinstein (CRR) discrete-time model to include collateral and FVA. We prove that this derived model is a discrete analogue of Piterbarg’s partial differential equation (PDE), which describes the price of a collateralized derivative. The fact that the two models coincide is also verified by numerical implementation of the results that we obtain.Journal of Risk and Financial Management2015-01-2681Article10.3390/jrfm801001717421911-80742015-01-26doi: 10.3390/jrfm8010017Chadd HunzingerCoenraad Labuschagne<![CDATA[IJGI, Vol. 4, Pages 150-171: CALPUFF and CAFOs: Air Pollution Modeling and Environmental Justice Analysis in the North Carolina Hog Industry]]>
http://www.mdpi.com/2220-9964/4/1/150
Concentrated animal feeding operations (CAFOs) produce large amounts of animal waste, which potentially pollutes air, soil and water and affects human health if not appropriately managed. This study uses meteorological and CAFO data and applies an air pollution dispersion model (CALPUFF) to estimate ammonia concentrations at locations downwind of hog CAFOs and to evaluate the disproportionate exposure of children, elderly, whites and minorities to the pollutant. Ammonia is one of the gases emitted by swine CAFOs and could affect human health. Local indicator of spatial autocorrelation (LISA) analysis uses census block demographic data to identify hot spots where both ammonia concentrations and the number of exposed vulnerable population are high. We limit our analysis to one watershed in North Carolina and compare environmental justice issues between 2000 and 2010. Our results show that the average ammonia concentrations in hot spots for 2000 and 2010 were 2.5–3-times higher than the average concentration in the entire watershed. The number of people living in the areas where ammonia concentrations exceeded the minimal risk level was 3647 people in 2000 and 3360 people in 2010. We recommend using air pollution dispersion models in future environmental justice studies to assess the impacts of the CAFOs and to address concerns regarding the health and quality of life of vulnerable populations.ISPRS International Journal of Geo-Information2015-01-2641Article10.3390/ijgi40101501501712220-99642015-01-26doi: 10.3390/ijgi4010150Yelena Ogneva-HimmelbergerLiyao HuangHao Xin<![CDATA[Electronics, Vol. 4, Pages 94-117: A Geometric Algebra Co-Processor for Color Edge Detection]]>
http://www.mdpi.com/2079-9292/4/1/94
This paper describes advancement in color edge detection, using a dedicated Geometric Algebra (GA) co-processor implemented on an Application Specific Integrated Circuit (ASIC). GA provides a rich set of geometric operations, giving the advantage that many signal and image processing operations become straightforward and the algorithms intuitive to design. The use of GA allows images to be represented with the three R, G, B color channels defined as a single entity, rather than separate quantities. A novel custom ASIC is proposed and fabricated that directly targets GA operations and results in significant performance improvement for color edge detection. Use of the hardware described in this paper also shows that the convolution operation with the rotor masks within GA belongs to a class of linear vector filters and can be applied to image or speech signals. The contribution of the proposed approach has been demonstrated by implementing three different types of edge detection schemes on the proposed hardware. The overall performance gains using the proposed GA Co-Processor over existing software approaches are more than 3.2× faster than GAIGEN and more than 2800× faster than GABLE. The performance of the fabricated GA co-processor is approximately an order of magnitude faster than previously published results for hardware implementations.Electronics2015-01-2641Article10.3390/electronics4010094941172079-92922015-01-26doi: 10.3390/electronics4010094Biswajit MishraPeter WilsonReuben Wilcock<![CDATA[Axioms, Vol. 4, Pages 71-83: Boas’ Formula and Sampling Theorem]]>
http://www.mdpi.com/2075-1680/4/1/71
In 1937, Boas gave a smart proof for an extension of the Bernstein theorem for trigonometric series. It is the purpose of the present note (i) to point out that a formula which Boas used in the proof is related with the Shannon sampling theorem; (ii) to present a generalized Parseval formula, which is suggested by the Boas’ formula; and (iii) to show that this provides a very smart derivation of the Shannon sampling theorem for a function which is the Fourier transform of a distribution involving the Dirac delta function. It is also shows that, by the argument giving Boas’ formula for the derivative f'(x) of a function f(x), we can derive the corresponding formula for f'''(x), by which we can obtain an upperbound of |f'''(x)+3R2f'(x)|. Discussions are given also on an extension of the Szegö theorem for trigonometric series, which Boas mentioned in the same paper.Axioms2015-01-2641Article10.3390/axioms401007171832075-16802015-01-26doi: 10.3390/axioms4010071Tohru MoritaKen-ichi Sato<![CDATA[Symmetry, Vol. 7, Pages 89-104: Can the Comparisons of Feature Locations Explain the Difficulty in Discriminating Mirror-Reflected Pairs of Geometrical Figures from Disoriented Identical Pairs?]]>
http://www.mdpi.com/2073-8994/7/1/89
The present experiment investigates whether patterns of shifts of feature locations could affect the same/different decisions of simultaneously presented pairs of geometrical figures. A shift of locations was defined as the angular distance from the location of a feature in one figure to the location of the same feature in another figure. It was hypothesized that the difficulty in discriminating mirror-reflected (or axisymmetric) pairs from disoriented identical pairs was caused by complex shifting patterns inherent in axisymmetric pairs. According to the shifts of the locations of the four structural features, five pair types were prepared. They could be ordered from completely identical to completely different in their shifts: identical 0/4 pairs, non-identical 1/4 pairs, non-identical 2/4 pairs = axisymmetric 2/4 pairs and non-identical 4/4 pairs. The latencies for non-identical pairs decreased with the increase of difference in the shifts of feature locations, indicating that serial, self-terminating comparisons of the shifts were applied to the discrimination of non-identical pairs from identical pairs. However, the longer latencies in axisymmetric 2/4 pairs than in non-identical 2/4 pairs suggested that the difficulty for axisymmetric pairs was not caused by the complex shifting patterns, and the difficulty was not satisfactorily explained by the comparisons of feature locations.Symmetry2015-01-2371Article10.3390/sym7010089891042073-89942015-01-23doi: 10.3390/sym7010089Fumio Kanbe<![CDATA[Electronics, Vol. 4, Pages 82-93: Motion Detection from Mobile Robots with Fuzzy Threshold Selection in Consecutive 2D Laser Scans]]>
http://www.mdpi.com/2079-9292/4/1/82
Motion detection and tracking is a relevant problem for mobile robots during navigation to avoid collisions in dynamic environments or in applications where service robots interact with humans. This paper presents a simple method to distinguish mobile obstacles from the environment that is based on applying fuzzy threshold selection to consecutive two-dimensional (2D) laser scans previously matched with robot odometry. The proposed method has been tested with the Auriga-α mobile robot in indoors to estimate the motion of nearby pedestrians.Electronics2015-01-2241Article10.3390/electronics401008282932079-92922015-01-22doi: 10.3390/electronics4010082María MartínezJorge MartínezJesús Morales<![CDATA[Information, Vol. 6, Pages 14-22: Modeling of Experimental Adsorption Isotherm Data]]>
http://www.mdpi.com/2078-2489/6/1/14
Adsorption is considered to be one of the most effective technologies widely used in global environmental protection areas. Modeling of experimental adsorption isotherm data is an essential way for predicting the mechanisms of adsorption, which will lead to an improvement in the area of adsorption science. In this paper, we employed three isotherm models, namely: Langmuir, Freundlich, and Dubinin-Radushkevich to correlate four sets of experimental adsorption isotherm data, which were obtained by batch tests in lab. The linearized and non-linearized isotherm models were compared and discussed. In order to determine the best fit isotherm model, the correlation coefficient (r2) and standard errors (S.E.) for each parameter were used to evaluate the data. The modeling results showed that non-linear Langmuir model could fit the data better than others, with relatively higher r2 values and smaller S.E. The linear Langmuir model had the highest value of r2, however, the maximum adsorption capacities estimated from linear Langmuir model were deviated from the experimental data.Information2015-01-2261Article10.3390/info601001414222078-24892015-01-22doi: 10.3390/info6010014Xunjun Chen<![CDATA[Mathematics, Vol. 3, Pages 16-28: Existence Results for Fractional Neutral Functional Differential Equations with Random Impulses]]>
http://www.mdpi.com/2227-7390/3/1/16
In this paper, we investigate the existence of solutions for the fractional neutral differential equations with random impulses. The results are obtained by using Krasnoselskii’s fixed point theorem. Examples are added to show applications of the main results.Mathematics2015-01-2131Communication10.3390/math301001616282227-73902015-01-21doi: 10.3390/math3010016Annamalai AngurajMullarithodi RanjiniMargarita RiveroJuan Trujillo<![CDATA[IJGI, Vol. 4, Pages 124-149: Transport Accessibility Analysis Using GIS: Assessing Sustainable Transport in London]]>
http://www.mdpi.com/2220-9964/4/1/124
Transport accessibility is an important driver of urban growth and key to the sustainable development of cities. This paper presents a simple GIS-based tool developed to allow the rapid analysis of accessibility by different transport modes. Designed to be flexible and use publicly-available data, this tool (built in ArcGIS) uses generalized cost to measure transport costs across networks including monetary and distance components. The utility of the tool is demonstrated on London, UK, showing the differing patterns of accessibility across the city by different modes. It is shown that these patterns can be examined spatially, by accessibility to particular destinations (e.g., employment locations), or as a global measure across a whole city system. A number of future infrastructure scenarios are tested, examining the potential for increasing the use of low-carbon forms of transport. It is shown that private car journeys are still the least cost mode choice in London, but that infrastructure investments can play a part in reducing the cost of more sustainable transport options.ISPRS International Journal of Geo-Information2015-01-2041Article10.3390/ijgi40101241241492220-99642015-01-20doi: 10.3390/ijgi4010124Alistair FordStuart BarrRichard DawsonPhilip James<![CDATA[Information, Vol. 6, Pages 3-13: The Kalman Filtering Blind Adaptive Multi-user Detector Based on Tracking Algorithm of Signal Subspace]]>
http://www.mdpi.com/2078-2489/6/1/3
Multi-user detection is an effective method to reduce multiple access interference in code division multiple access (CDMA) systems. This paper discusses a signal subspace based blind adaptive multiuser detector and a Kalman filtering blind adaptive multiuser detector. Combining them together, a new Kalman filtering blind adaptive multiuser detector based on a tracking algorithm of the signal subspace is proposed. Analysis and simulation show that the proposed blind multiuser detector achieves better suppression of multiple access interference and has a higher convergence rate.Information2015-01-2061Article10.3390/info60100033132078-24892015-01-20doi: 10.3390/info6010003Liqing ZhouHenry LeungPeng XuGuobao RuQuansheng ZhaoDa Xu<![CDATA[Technologies, Vol. 3, Pages 1-18: Using Microwave Energy to Synthesize Light Weight/Energy Saving Magnesium Based Materials: A Review]]>
http://www.mdpi.com/2227-7080/3/1/1
Microwave energy can be used for the processing of a wide variety of materials. It is used most commonly for the heating of food and has been increasingly applied for processing of polymers; ceramics; metals; minerals and composites. The use of microwave energy allows rapid and volumetric heating where heat is generated from within the material instead of via radiative heat transfer from external heating elements. This paper aims to provide a review on the use of energy efficient and environment friendly microwave energy route to synthesize magnesium based materials reinforced with various types of metallic and ceramic reinforcements. Magnesium composites are extremely attractive for weight critical applications in automotive; aerospace; electronics and transportation sectors. The magnesium composites were prepared using blend—compact—microwave sintering—extrusion methodology. Microwave sintering allowed a significant reduction of 80% in both processing time and energy consumption over conventional sintering without any detrimental effect on the properties of the synthesized magnesium composites. Physical; microstructure and mechanical properties of microwave sintered magnesium composites will also be discussed and compared with magnesium composites processed by conventional liquid and solid processing techniques.Technologies2015-01-2031Review10.3390/technologies30100011182227-70802015-01-20doi: 10.3390/technologies3010001Wai WongManoj Gupta<![CDATA[JRFM, Vol. 8, Pages 2-16: State Prices and Implementation of the Recovery Theorem]]>
http://www.mdpi.com/1911-8074/8/1/2
It is generally held that derivative prices do not contain useful predictive information, that is, information relating to the distribution of future financial variables under the real-world measure. This is because the market’s implicit forecast of the future becomes entangled with market risk preferences during derivative price formation. A result derived by Ross [1], however, recovers the real-world distribution of an equity index, requiring only current prices and mild restrictions on risk preferences. In addition to being of great interest to the theorist, the potential practical value of the result is considerable. This paper addresses implementation of the Ross Recovery Theorem. The theorem is formalised, extended, proved and discussed. Obstacles to application are identified and a workable implementation methodology is developed.Journal of Risk and Financial Management2015-01-1981Article10.3390/jrfm80100022161911-80742015-01-19doi: 10.3390/jrfm8010002Alex Backwell<![CDATA[Axioms, Vol. 4, Pages 32-70: Azumaya Monads and Comonads]]>
http://www.mdpi.com/2075-1680/4/1/32
The definition of Azumaya algebras over commutative rings \(R\) requires the tensor product of modules over \(R\) and the twist map for the tensor product of any two \(R\)-modules. Similar constructions are available in braided monoidal categories, and Azumaya algebras were defined in these settings. Here, we introduce Azumaya monads on any category \(\mathbb{A}\) by considering a monad \((F,m,e)\) on \(\mathbb{A}\) endowed with a distributive law \(\lambda: FF\to FF\) satisfying the Yang–Baxter equation (BD%please define -law). This allows to introduce an opposite monad \((F^\lambda,m\cdot \lambda,e)\) and a monad structure on \(FF^\lambda\). The quadruple \((F,m,e,\lambda)\) is called an Azumaya monad, provided that the canonical comparison functor induces an equivalence between the category \(\mathbb{A}\) and the category of \(FF^\lambda\)-modules. Properties and characterizations of these monads are studied, in particular for the case when \(F\) allows for a right adjoint functor. Dual to Azumaya monads, we define Azumaya comonads and investigate the interplay between these notions. In braided categories (V\(,\otimes,I,\tau)\), for any V-algebra \(A\), the braiding induces a BD-law \(\tau_{A,A}:A\otimes A\to A\otimes A\), and \(A\) is called left (right) Azumaya, provided the monad \(A\otimes-\) (resp. \(-\otimes A\)) is Azumaya. If \(\tau\) is a symmetry or if the category V admits equalizers and coequalizers, the notions of left and right Azumaya algebras coincide.Axioms2015-01-1941Article10.3390/axioms401003232702075-16802015-01-19doi: 10.3390/axioms4010032Bachuki MesablishviliRobert Wisbauer<![CDATA[Mathematics, Vol. 3, Pages 2-15: On θ-Congruent Numbers, Rational Squares in Arithmetic Progressions, Concordant Forms and Elliptic Curves]]>
http://www.mdpi.com/2227-7390/3/1/2
The correspondence between right triangles with rational sides, triplets of rational squares in arithmetic succession and integral solutions of certain quadratic forms is well-known. We show how this correspondence can be extended to the generalized notions of rational θ-triangles, rational squares occurring in arithmetic progressions and concordant forms. In our approach we establish one-to-one mappings to rational points on certain elliptic curves and examine in detail the role of solutions of the θ-congruent number problem and the concordant form problem associated with nontrivial torsion points on the corresponding elliptic curves. This approach allows us to combine and extend some disjoint results obtained by a number of authors, to clarify some statements in the literature and to answer some hitherto open questions.Mathematics2015-01-1931Article10.3390/math30100022152227-73902015-01-19doi: 10.3390/math3010002Erich SelderKarlheinz Spindler<![CDATA[Algorithms, Vol. 8, Pages 3-18: Networked Control System Time-Delay Compensation Based on Time-Delay Prediction and Improved Implicit GPC]]>
http://www.mdpi.com/1999-4893/8/1/3
The random time delay in a networked control system can usually deteriorate the control performance and stability of the networked control system. In order to solve this problem, this paper puts forward a networked control system random time-delay compensation method based on time-delay prediction and improved implicit generalized predictive control (GPC). The least squares support vector machine is used to predict the future time delay of network. The parameters of the least squares support vector machine time-delay prediction model are difficult to determine, and the genetic algorithm is used for least squares support vector machine optimal prediction parameter optimization. Then, an improved implicit generalized predictive control method is adopted to compensate for the time delay. The simulation results show that the method in this paper has high prediction accuracy and a good compensation effect for the random time delay of the networked control system, has a small amount of on-line calculation and that the output response and control stability of the system are improved.Algorithms2015-01-1981Article10.3390/a80100033181999-48932015-01-19doi: 10.3390/a8010003Zhong-Da TianShu-Jiang LiYan-Hong WangHong-Xia Yu<![CDATA[Risks, Vol. 3, Pages 35-60: Safety Margins for Systematic Biometric and Financial Risk in a Semi-Markov Life Insurance Framework]]>
http://www.mdpi.com/2227-9091/3/1/35
Insurance companies use conservative first order valuation bases to calculate insurance premiums and reserves. These valuation bases have a significant impact on the insurer’s solvency and on the premiums of the insurance products. Safety margins for systematic biometric and financial risk are in practice typically chosen as time-constant percentages on top of the best estimate transition intensities. We develop a risk-oriented method for the allocation of a total safety margin to the single safety margins at each point in time and each state. In a case study, we demonstrate the suitability of the proposed method in different frameworks. The results show that the traditional method yields an unwanted variability of the safety level with respect to time, whereas the variability can be significantly reduced by the new method. Furthermore, the case study supports the German 60 percent rule for the technical interest rate.Risks2015-01-1931Article10.3390/risks301003535602227-90912015-01-19doi: 10.3390/risks3010035Andreas Niemeyer<![CDATA[Risks, Vol. 3, Pages 26-34: Paradox-Proof Utility Functions for Heavy-Tailed Payoffs: Two Instructive Two-Envelope Problems]]>
http://www.mdpi.com/2227-9091/3/1/26
We identify restrictions on a decision maker’s utility function that are both necessary and sufficient to preserve dominance reasoning in each of two versions of the Two-Envelope Paradox (TEP). For the classical TEP, the utility function must satisfy a certain recurrence inequality. For the St. Petersburg TEP, the utility function must be bounded above asymptotically by a power function, which can be tightened to a constant. By determining the weakest conditions for dominance reasoning to hold, the article settles an open question in the research literature. Remarkably, neither constant-bounded utility nor finite expected utility is necessary for resolving the classical TEP; instead, finite expected utility is both necessary and sufficient for resolving the St. Petersburg TEP.Risks2015-01-1931Article10.3390/risks301002626342227-90912015-01-19doi: 10.3390/risks3010026Michael Powers<![CDATA[Econometrics, Vol. 3, Pages 2-54: Modeling Autoregressive Processes with Moving-Quantiles-Implied Nonlinearity]]>
http://www.mdpi.com/2225-1146/3/1/2
We introduce and investigate some properties of a class of nonlinear time series models based on the moving sample quantiles in the autoregressive data generating process. We derive a test fit to detect this type of nonlinearity. Using the daily realized volatility data of Standard &amp; Poor’s 500 (S&amp;P 500) and several other indices, we obtained good performance using these models in an out-of-sample forecasting exercise compared with the forecasts obtained based on the usual linear heterogeneous autoregressive and other models of realized volatility.Econometrics2015-01-1631Article10.3390/econometrics30100022542225-11462015-01-16doi: 10.3390/econometrics3010002Isao IshidaVirmantas Kvedaras<![CDATA[Symmetry, Vol. 7, Pages 67-88: Dihedral Reductions of Cyclic DNA Sequences]]>
http://www.mdpi.com/2073-8994/7/1/67
The data-analytic methodology of dihedral reductions for cyclic orbits of distinct-base codons is described both in terms of Fourier analysis over the dihedral groups and in (algebraically equivalent) terms of canonical projections. Numerical evaluations are presented for discrete and continuous scalar data indexed by cyclic orbits.Symmetry2015-01-1671Article10.3390/sym701006767882073-89942015-01-16doi: 10.3390/sym7010067Marlos Viana<![CDATA[IJGI, Vol. 4, Pages 105-123: Analyzing the Correlation between Deer Habitat and the Component of the Risk for Lyme Disease in Eastern Ontario, Canada: A GIS-Based Approach]]>
http://www.mdpi.com/2220-9964/4/1/105
Lyme borreliosis, caused by the bacterium, Borrelia burgdorferi, is an emerging vector-borne infectious disease in Canada. According to the Public Health Agency of Canada (PHAC), by the year 2020, 80% of Canadians will live in Lyme endemic areas. An understanding of the association of Ixodes scapularis, the main vector of Lyme disease, with it hosts is a fundamental component in assessing changes in the spatial distribution of human risk for Lyme disease. Through the application of Geographic Information System (GIS) mapping methods and spatial analysis techniques, this study examines the population dynamics of the black-legged Lyme tick and its primary host, the white-tailed deer, in eastern Ontario, Canada. By developing a habitat suitability model through a GIS-based multi-criteria decision making (MCDM) analysis, the relationship of the deer habitat suitability map was generated and the results were compared with deer harvest data. Tick submission data collected from two public health units between 2006 and 2012 were used to explore the relationship between endemic ticks and deer habitat suitability in eastern Ontario. The positive correlation demonstrated between the deer habitat suitability model and deer harvest data allows us to further analyze the association between deer habitat and black-legged ticks in our study area. Our results revealed that the high tick submission number corresponds with the high suitability. These results are useful for developing management strategies that aim to prevent Lyme from becoming a threat to public health in Canada. Further studies are required to investigate how tick survival, behaviour and seasonal activity may change with projected climate change.ISPRS International Journal of Geo-Information2015-01-1541Article10.3390/ijgi40101051051232220-99642015-01-15doi: 10.3390/ijgi4010105Dongmei ChenHaydi WongPaul BelangerKieran MooreMary PetersonJohn Cunningham<![CDATA[Administrative Sciences, Vol. 5, Pages 2-26: Vaccination Games with Peer Effects in a Heterogeneous Hospital Worker Population]]>
http://www.mdpi.com/2076-3387/5/1/2
We develop a game theoretic model to analyze the Nash equilibrium of vaccine decisions in a hospital population with heterogeneous contacts. We use the model in conjunction with person-to-person contact data within a large university hospital. We simulate, using agent-based models, the probability of infection for various worker types in the data and use these probabilities to identify the Nash equilibrium vaccine choices of hospital workers. The analysis suggests that there may be large differences in vaccination rates among hospital worker groups. We extend the model to include peer effects within the game. The peer effects may create additional equilibria or may further cement existing equilibria depending on parameter values. Further, depending on the magnitude of the peer effects and the costs of infection and vaccination, peer effects may increase or decrease differences in worker group vaccination rates within the hospital.Administrative Sciences2015-01-1451Article10.3390/admsci50100022262076-33872015-01-14doi: 10.3390/admsci5010002Troy TassierPhilip PolgreenAlberto Segre<![CDATA[Computation, Vol. 3, Pages 2-28: Computational Studies of the Intestinal Host-Microbiota Interactome]]>
http://www.mdpi.com/2079-3197/3/1/2
A large and growing body of research implicates aberrant immune response and compositional shifts of the intestinal microbiota in the pathogenesis of many intestinal disorders. The molecular and physical interaction between the host and the microbiota, known as the host-microbiota interactome, is one of the key drivers in the pathophysiology of many of these disorders. This host-microbiota interactome is a set of dynamic and complex processes, and needs to be treated as a distinct entity and subject for study. Disentangling this complex web of interactions will require novel approaches, using a combination of data-driven bioinformatics with knowledge-driven computational modeling. This review describes the computational approaches for investigating the host-microbiota interactome, with emphasis on the human intestinal tract and innate immunity, and highlights open challenges and existing gaps in the computation methodology for advancing our knowledge about this important facet of human health.Computation2015-01-1431Review10.3390/computation30100022282079-31972015-01-14doi: 10.3390/computation3010002Scott ChristleyChase CockrellGary An<![CDATA[Symmetry, Vol. 7, Pages 53-66: Output Effect Evaluation Based on Input Features in Neural Incremental Attribute Learning for Better Classification Performance]]>
http://www.mdpi.com/2073-8994/7/1/53
Machine learning is a very important approach to pattern classification. This paper provides a better insight into Incremental Attribute Learning (IAL) with further analysis as to why it can exhibit better performance than conventional batch training. IAL is a novel supervised machine learning strategy, which gradually trains features in one or more chunks. Previous research showed that IAL can obtain lower classification error rates than a conventional batch training approach. Yet the reason for that is still not very clear. In this study, the feasibility of IAL is verified by mathematical approaches. Moreover, experimental results derived by IAL neural networks on benchmarks also confirm the mathematical validation.Symmetry2015-01-1471Article10.3390/sym701005353662073-89942015-01-14doi: 10.3390/sym7010053Ting WangSheng-Uei GuanKa ManJong ParkHui-Huang Hsu<![CDATA[Symmetry, Vol. 7, Pages 43-52: Development of Guanidine-Bisurea Bifunctional Organocatalyst Bearing Chirality at the Inner and Outer Sides of the Urea Groups, and Application to Enantioselective α-Hydroxylation of Pyranoindolizine Intermediate for Camptothecin Synthesis]]>
http://www.mdpi.com/2073-8994/7/1/43
Pyranoindolizine is a tricyclic structure found in various biologically active compounds, such as camptothecin (CPT) and its derivatives. In the case of CPTs, the chirality at the α-position in the α-hydroxyl lactone moiety of pyranoindolizine is important for the antitumor activity. This paper deals with enantioselective oxidation of the α-position in pyranoindolizine lactone, which corresponds at C20 in CPT, with cumene hydroperoxide (CHP) in the presence of newly synthesized guanidine-bisurea bifunctional organocatalysts bearing chirality on both the inner and outer sides of the urea groups.Symmetry2015-01-1471Article10.3390/sym701004343522073-89942015-01-14doi: 10.3390/sym7010043Minami OdagiTatsuya WatanabeKazuo Nagasawa<![CDATA[JSAN, Vol. 4, Pages 1: Acknowledgement to Reviewers of the Journal of Sensor and Actuator Networks in 2014]]>
http://www.mdpi.com/2224-2708/4/1/1
The editors of the Journal of Sensor and Actuator Networks would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...]Journal of Sensor and Actuator Networks2015-01-1341Editorial10.3390/jsan4010001112224-27082015-01-13doi: 10.3390/jsan4010001 Journal of Sensor Actuator Networks Editorial Office<![CDATA[Electronics, Vol. 4, Pages 59-81: Motion Planning of Autonomous Vehicles on a Dual Carriageway without Speed Lanes]]>
http://www.mdpi.com/2079-9292/4/1/59
The problem of motion planning of an autonomous vehicle amidst other vehicles on a straight road is considered. Traffic in a number of countries is unorganized, where the vehicles do not move within predefined speed lanes. In this paper, we formulate a mechanism wherein an autonomous vehicle may travel on the “wrong” side in order to overtake a vehicle. Challenges include assessing a possible overtaking opportunity, cooperating with other vehicles, partial driving on the “wrong” side of the road and safely going to and returning from the “wrong” side. The experimental results presented show vehicles cooperating to accomplish overtaking manoeuvres.Electronics2015-01-1341Article10.3390/electronics401005959812079-92922015-01-13doi: 10.3390/electronics4010059Rahul KalaKevin Warwick<![CDATA[IJGI, Vol. 4, Pages 87-104: Visual Overlay on OpenStreetMap Data to Support Spatial Exploration of Urban Environments]]>
http://www.mdpi.com/2220-9964/4/1/87
Increasing volumes of spatial data about urban areas are captured and made available via volunteered geographic information (VGI) sources, such as OpenStreetMap (OSM). Hence, new opportunities arise for regional exploration that can lead to improvements in the lives of citizens through spatial decision support. We believe that the VGI data of the urban environment could be used to present a constructive overview of the regional infrastructure with the advent of web technologies. Current location-based services provide general map-based information for the end users with conventional local search functionality, and hence, the presentation of the rich urban information is limited. In this work, we analyze the OSM data to classify the geo entities into consequential categories with facilities, landscape and land use distribution. We employ a visual overlay of heat map and interactive visualizations to present the regional characterization on OSM data classification. In the proposed interface, users are allowed to express a variety of spatial queries to exemplify their geographic interests. They can compare the characterization of urban areas with respect to multiple spatial dimensions of interest and can search for the most suitable region. The search experience is further enhanced via efficient optimization and interaction methods to support the decision making of end users. We report the end user acceptability and efficiency of the proposed system via usability studies and performance analysis comparison.ISPRS International Journal of Geo-Information2015-01-1341Article10.3390/ijgi4010087871042220-99642015-01-13doi: 10.3390/ijgi4010087Chandan KumarWilko HeutenSusanne Boll<![CDATA[JRFM, Vol. 8, Pages 1: Acknowledgement to Reviewers of the Journal of Risk and Financial Management]]>
http://www.mdpi.com/1911-8074/8/1/1
The editors of the Journal of Risk and Financial Management would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...]Journal of Risk and Financial Management2015-01-1281Editorial10.3390/jrfm8010001111911-80742015-01-12doi: 10.3390/jrfm8010001 Journal of Risk Financial Management Editorial Office<![CDATA[Econometrics, Vol. 3, Pages 1: Acknowledgement to Reviewers of Econometrics in 2014]]>
http://www.mdpi.com/2225-1146/3/1/1
The editors of Econometrics would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...]Econometrics2015-01-0931Editorial10.3390/econometrics3010001112225-11462015-01-09doi: 10.3390/econometrics3010001 Econometrics Editorial Office<![CDATA[Economies, Vol. 3, Pages 1: Acknowledgement to Reviewers of Economies in 2014]]>
http://www.mdpi.com/2227-7099/3/1/1
The editors of Economies would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...]Economies2015-01-0931Editorial10.3390/economies3010001112227-70992015-01-09doi: 10.3390/economies3010001 Economies Editorial Office<![CDATA[IJGI, Vol. 4, Pages 62-86: The Use of Exhaustive Micro-Data Firm Databases for Economic Geography: The Issues of Geocoding and Usability in the Case of the Amadeus Database]]>
http://www.mdpi.com/2220-9964/4/1/62
Economic geography has begun to explore the options involved in micro-data. New databases have become available and new techniques and an increase in computer power allow their treatment. However, two major issues impede the use of these datasets: the lack of geocoded spatial location and lack of exhaustivity in coverage. In this article, I explore the possibilities of using large micro-scale firm databases for economic geography in Europe. I show that current evolution in European official spatial data dissemination alows for geocoding of such databases using means that are accessible for researchers with minimal programming knowledge. For the specific case of the Amadeus database of the Bureau Van Dijk, I show that its limitations in terms of coverage have to be taken into acount, but do not hinder its use for analysis. Resulting maps show how the data allows to go further than classic databases such as the Eurostat Structural Business Statistics.ISPRS International Journal of Geo-Information2015-01-0941Article10.3390/ijgi401006262862220-99642015-01-09doi: 10.3390/ijgi4010062Moritz Lennert<![CDATA[Computation, Vol. 3, Pages 1: Acknowledgement to Reviewers of Computation in 2014]]>
http://www.mdpi.com/2079-3197/3/1/1
The editors of Computation would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...]Computation2015-01-0931Editorial10.3390/computation3010001112079-31972015-01-09doi: 10.3390/computation3010001 Computation Editorial Office<![CDATA[Computers, Vol. 4, Pages 1: Acknowledgement to Reviewers of Computers in 2014]]>
http://www.mdpi.com/2073-431X/4/1/1
The editors of Computers would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...]Computers2015-01-0941Editorial10.3390/computers4010001112073-431X2015-01-09doi: 10.3390/computers4010001 Computers Editorial Office<![CDATA[IJFS, Vol. 3, Pages 1-2: Acknowledgement to Reviewers of the International Journal of Financial Studies in 2014]]>
http://www.mdpi.com/2227-7072/3/1/1
The editors of the International Journal of Financial Studies would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014: [...]International Journal of Financial Studies2015-01-0931Editorial10.3390/ijfs3010001122227-70722015-01-09doi: 10.3390/ijfs3010001 International Journal of Financial Studies Editorial Office<![CDATA[Mathematics, Vol. 3, Pages 1: Acknowledgement to Reviewers of Mathematics in 2014]]>
http://www.mdpi.com/2227-7390/3/1/1
The editors of Mathematics would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...]Mathematics2015-01-0931Editorial10.3390/math3010001112227-73902015-01-09doi: 10.3390/math3010001 Mathematics Editorial Office<![CDATA[Administrative Sciences, Vol. 5, Pages 1: Acknowledgement to Reviewers of Administrative Sciences in 2014]]>
http://www.mdpi.com/2076-3387/5/1/1
The editors of Administrative Sciences would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...]Administrative Sciences2015-01-0951Editorial10.3390/admsci5010001112076-33872015-01-09doi: 10.3390/admsci5010001 Administrative Sciences Editorial Office<![CDATA[Future Internet, Vol. 7, Pages 24-25: Acknowledgement to Reviewers of Future Internet in 2014]]>
http://www.mdpi.com/1999-5903/7/1/24
The editors of Future Internet would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...]Future Internet2015-01-0971Editorial10.3390/fi701002424251999-59032015-01-09doi: 10.3390/fi7010024 Future Internet Editorial Office<![CDATA[Electronics, Vol. 4, Pages 37-58: On the Impact of Building Attenuation Models in VANET Simulations of Urban Scenarios]]>
http://www.mdpi.com/2079-9292/4/1/37
Buildings are important elements of cities for VANETs, since these obstacles may attenuate communications between vehicles. Consequently, the impact of buildings has to be considered as part of the attenuation model in VANET simulations of urban scenarios. However, the more elaborated the model, the more information needs to be processed during the simulation, which implies longer processing times. This complexity in simulations is not always worth it, because simplified channel models occasionally offer very accurate results. We compare three approaches to model the impact of buildings in the channel model of simulated VANETs in two urban scenarios. The simulation results for our evaluation scenarios of a traffic-efficiency application indicate that modeling the influence of buildings in urban areas as the total absence of communication between vehicles gives similar results to modeling such influence in a more realistic fashion and could be considered a conservative bound in the performance metrics.Electronics2015-01-0841Article10.3390/electronics401003737582079-92922015-01-08doi: 10.3390/electronics4010037Luis Urquiza-AguiarCarolina Tripp-BarbaJosé Estrada-JiménezMónica Igartua<![CDATA[Electronics, Vol. 4, Pages 35-36: Acknowledgement to Reviewers of Electronics in 2014]]>
http://www.mdpi.com/2079-9292/4/1/35
The editors of Electronics would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...]Electronics2015-01-0841Editorial10.3390/electronics401003535362079-92922015-01-08doi: 10.3390/electronics4010035 Electronics Editorial Office<![CDATA[Systems, Vol. 3, Pages 4-5: Acknowledgement to Reviewers of Systems in 2014]]>
http://www.mdpi.com/2079-8954/3/1/4
The editors of Systems would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...]Systems2015-01-0831Editorial10.3390/systems3010004452079-89542015-01-08doi: 10.3390/systems3010004 Systems Editorial Office<![CDATA[Robotics, Vol. 4, Pages 23-24: Acknowledgement to Reviewers of Robotics in 2014]]>
http://www.mdpi.com/2218-6581/4/1/23
The editors of Robotics would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...]Robotics2015-01-0841Editorial10.3390/robotics401002323242218-65812015-01-08doi: 10.3390/robotics4010023 Robotics Editorial Office<![CDATA[Axioms, Vol. 4, Pages 30-31: Acknowledgement to Reviewers of Axioms in 2014]]>
http://www.mdpi.com/2075-1680/4/1/30
The editors of Axioms would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...]Axioms2015-01-0841Editorial10.3390/axioms401003030312075-16802015-01-08doi: 10.3390/axioms4010030 Axioms Editorial Office<![CDATA[Risks, Vol. 3, Pages 24-25: Acknowledgement to Reviewers of Risks in 2014]]>
http://www.mdpi.com/2227-9091/3/1/24
The editors of Risks would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...]Risks2015-01-0831Editorial10.3390/risks301002424252227-90912015-01-08doi: 10.3390/risks3010024 Risks Editorial Office<![CDATA[Algorithms, Vol. 8, Pages 1-2: Acknowledgement to Reviewers of Algorithms in 2014]]>
http://www.mdpi.com/1999-4893/8/1/1
The editors of Algorithms would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...]Algorithms2015-01-0881Editorial10.3390/a8010001121999-48932015-01-08doi: 10.3390/a8010001 Algorithms Editorial Office<![CDATA[Information, Vol. 6, Pages 1-2: Acknowledgement to Reviewers of Information in 2014]]>
http://www.mdpi.com/2078-2489/6/1/1
The editors of Information would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...]Information2015-01-0761Editorial10.3390/info6010001122078-24892015-01-07doi: 10.3390/info6010001 Information Editorial Office<![CDATA[IJGI, Vol. 4, Pages 59-61: Acknowledgement to Reviewers of the ISPRS International Journal of Geo-Information in 2014]]>
http://www.mdpi.com/2220-9964/4/1/59
The editors of the ISPRS International Journal of Geo-Information would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...]ISPRS International Journal of Geo-Information2015-01-0741Editorial10.3390/ijgi401005959612220-99642015-01-07doi: 10.3390/ijgi4010059 IJGI Editorial Office<![CDATA[Symmetry, Vol. 7, Pages 40-42: Acknowledgement to Reviewers of Symmetry in 2014]]>
http://www.mdpi.com/2073-8994/7/1/40
The editors of Symmetry would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...]Symmetry2015-01-0771Editorial10.3390/sym701004040422073-89942015-01-07doi: 10.3390/sym7010040 Symmetry Editorial Office<![CDATA[Risks, Vol. 3, Pages 1-23: Inhomogeneous Long-Range Percolation for Real-Life Network Modeling]]>
http://www.mdpi.com/2227-9091/3/1/1
The study of random graphs has become very popular for real-life network modeling, such as social networks or financial networks. Inhomogeneous long-range percolation (or scale-free percolation) on the lattice Zd, d ≥ 1, is a particular attractive example of a random graph model because it fulfills several stylized facts of real-life networks. For this model, various geometric properties, such as the percolation behavior, the degree distribution and graph distances, have been analyzed. In the present paper, we complement the picture of graph distances and we prove continuity of the percolation probability in the phase transition point. We also provide an illustration of the model connected to financial networks.Risks2015-01-0631Article10.3390/risks30100011232227-90912015-01-06doi: 10.3390/risks3010001Philippe DeprezRajat HazraMario Wüthrich<![CDATA[Future Internet, Vol. 7, Pages 1-23: Geographic Ontologies, Gazetteers and Multilingualism]]>
http://www.mdpi.com/1999-5903/7/1/1
Different languages imply different visions of space, so that terminologies are different in geographic ontologies. In addition to their geometric shapes, geographic features have names, sometimes different in diverse languages. In addition, the role of gazetteers, as dictionaries of place names (toponyms), is to maintain relations between place names and location. The scope of geographic information retrieval is to search for geographic information not against a database, but against the whole Internet: but the Internet stores information in different languages, and it is of paramount importance not to remain stuck to a unique language. In this paper, our first step is to clarify the links between geographic objects as computer representations of geographic features, ontologies and gazetteers designed in various languages. Then, we propose some inference rules for matching not only types, but also relations in geographic ontologies with the assistance of gazetteers.Future Internet2015-01-0571Article10.3390/fi70100011231999-59032015-01-05doi: 10.3390/fi7010001Robert Laurini<![CDATA[Electronics, Vol. 4, Pages 1-34: Improving Performance and Versatility of Systems Based on Single-Frequency DFT Detectors Such as AD5933]]>
http://www.mdpi.com/2079-9292/4/1/1
Turning grand concepts such as the Internet of Things (IoT) and Smart Cities into reality requires the development and deployment of a wide variety of computing devices incorporated into the Internet infrastructure. Unsupervised sensing is the cornerstone capability that these devices must have to perform useful functions, while also having low cost of acquisition and ownership, little energy consumption and a small footprint. Impedimetric sensing systems based on the so-called single-frequency DFT detectors possess many of these desirable attributes and are often introduced in remote monitoring and wearable devices. This study presents new methods of improving performance of such detectors. It demonstrates that the main source of systematic errors is the discontinuous test phasor causing the crosstalk between the in-phase and quadrature outputs and the leakage of the input signal. The study derives expressions for these errors as a function of the number of samples and operating frequency, and provides methods for correction. The proposed methods are applied to the operation of a practical device—a network analyzer integrated circuit AD5933—and discussed in detail. These methods achieve complete elimination of leakage errors and expansion of the low limit of the operation frequency range by nearly two decades without additional hardware.Electronics2014-12-3141Article10.3390/electronics40100011342079-92922014-12-31doi: 10.3390/electronics4010001Leonid Matsiev<![CDATA[IJGI, Vol. 4, Pages 47-58: Geospatial Technology: A Tool to Aid in the Elimination of Malaria in Bangladesh]]>
http://www.mdpi.com/2220-9964/4/1/47
Bangladesh is a malaria endemic country. There are 13 districts in the country bordering India and Myanmar that are at risk of malaria. The majority of malaria morbidity and mortality cases are in the Chittagong Hill Tracts, the mountainous southeastern region of Bangladesh. In recent years, malaria burden has declined in the country. In this study, we reviewed and summarized published data (through 2014) on the use of geospatial technologies on malaria epidemiology in Bangladesh and outlined potential contributions of geospatial technologies for eliminating malaria in the country. We completed a literature review using “malaria, Bangladesh” search terms and found 218 articles published in peer-reviewed journals listed in PubMed. After a detailed review, 201 articles were excluded because they did not meet our inclusion criteria, 17 articles were selected for final evaluation. Published studies indicated geospatial technologies tools (Geographic Information System, Global Positioning System, and Remote Sensing) were used to determine vector-breeding sites, land cover classification, accessibility to health facility, treatment seeking behaviors, and risk mapping at the household, regional, and national levels in Bangladesh. To achieve the goal of malaria elimination in Bangladesh, we concluded that further research using geospatial technologies should be integrated into the country’s ongoing surveillance system to identify and better assess progress towards malaria elimination.ISPRS International Journal of Geo-Information2014-12-3141Article10.3390/ijgi401004747582220-99642014-12-31doi: 10.3390/ijgi4010047Karen KirkM. HaqMohammad AlamUbydul Haque<![CDATA[Symmetry, Vol. 7, Pages 32-39: Topology and the Visualization of Space]]>
http://www.mdpi.com/2073-8994/7/1/32
Overlapping patterns provide the diagrammatics for four-dimensional space. If these patterns are three-dimensional lattices, and if one imagines them extended in three-dimensional space, then the diagram makes a model of physical space.Symmetry2014-12-3071Article10.3390/sym701003232392073-89942014-12-30doi: 10.3390/sym7010032Tony Robbin<![CDATA[IJGI, Vol. 4, Pages 32-46: Examining Personal Air Pollution Exposure, Intake, and Health Danger Zone Using Time Geography and 3D Geovisualization]]>
http://www.mdpi.com/2220-9964/4/1/32
Expanding traditional time geography, this study examines personal exposure to air pollution and personal pollutant intake, and defines personal health danger zones by accounting for individual level space-time behavior. A 3D personal air pollution and health risk map is constructed to visualize individual space-time path, personal Air Quality Indexes (AQIs), and personal health danger zones. Personal air pollution exposure level and its variation through space and time is measured by a portable air pollutant sensor coupled with a portable GPS unit. Personal pollutant intake is estimated by accounting for air pollutant concentration in immediate surroundings, individual’s biophysical characteristics, and individual’s space-time activities. Personal air pollution danger zones are defined by comparing personal pollutant intake with air quality standard; these zones are particular space-time-activity segments along an individual’s space-time path. Being able to identify personal air pollution danger zones can help plan for proper actions aiming at controlling health impacts from air pollution. As a case study, this paper reports on an examination and visualization of an individual’s two-day ozone exposure, intake and danger zones in Houston, Texas.ISPRS International Journal of Geo-Information2014-12-3041Article10.3390/ijgi401003232462220-99642014-12-30doi: 10.3390/ijgi4010032Yongmei LuTianfang Fang<![CDATA[IJGI, Vol. 4, Pages 1-31: Measure of Landmark Semantic Salience through Geosocial Data Streams]]>
http://www.mdpi.com/2220-9964/4/1/1
Research in the area of spatial cognition demonstrated that references to landmarks are essential in the communication and the interpretation of wayfinding instructions for human being. In order to detect landmarks, a model for the assessment of their salience has been previously developed by Raubal and Winter. According to their model, landmark salience is divided into three categories: visual, structural, and semantic. Several solutions have been proposed to automatically detect landmarks on the basis of these categories. Due to a lack of relevant data, semantic salience has been frequently reduced to objects’ historical and cultural significance. Social dimension (i.e., the way an object is practiced and recognized by a person or a group of people) is systematically excluded from the measure of landmark semantic salience even though it represents an important component. Since the advent of mobile Internet and smartphones, the production of geolocated content from social web platforms—also described as geosocial data—became commonplace. Actually, these data allow us to have a better understanding of the local geographic knowledge. Therefore, we argue that geosocial data, especially Social Location Sharing datasets, represent a reliable source of information to precisely measure landmark semantic salience in urban area.ISPRS International Journal of Geo-Information2014-12-3041Article10.3390/ijgi40100011312220-99642014-12-30doi: 10.3390/ijgi4010001Teriitutea QuesnotStéphane Roche<![CDATA[Symmetry, Vol. 7, Pages 15-31: Effect of Tensor Correlations on the Density Dependence of the Nuclear Symmetry Energy]]>
http://www.mdpi.com/2073-8994/7/1/15
We analyze the effect of the tensor force and other components of the nucleon-nucleon interaction on the nuclear symmetry energy and its density dependence by using the Hellmann–Feynman theorem. The analysis is performed within the microscopic Brueckner–Hartree–Fock approach using the Argonne V18 potential plus a Urbana IX three-nucleon force. Our results show that the potential part of the nuclear Hamiltonian, and in particular its tensor component, gives the largest contribution to the symmetry energy. The decomposition of the symmetry energy into a kinetic part and a potential energy part provides physical insight on the correlated nature of the system, indicating that pure neutron matter is less correlated than symmetric nuclear matter.Symmetry2014-12-2971Article10.3390/sym701001515312073-89942014-12-29doi: 10.3390/sym7010015Isaac VidañaConstança ProvidênciaArtur Polls<![CDATA[Symmetry, Vol. 7, Pages 1-14: A Study on Electronic-Money Technology Using Near Field Communication]]>
http://www.mdpi.com/2073-8994/7/1/1
Recently, due to the introduction of NFC (Near Field Communication), it has become possible to make easy electronic payments. Therefore, a secure communication method is necessary in these environments. NFC can be said to be relatively safe compared to other communication methods, because it carries out communications within 10 cm. However, it has made possible the risk of impersonation attacks by a disguised reader, leaving user information on the reader. In order to solve these problems, in this paper, we propose an authentication scheme that can reduce the weight of computation by using only a hash function and XOR (eXclusive OR) operation algorithms. This paper also shows that our method is safe, since it leaves no information with the other party.Symmetry2014-12-2671Article10.3390/sym70100011142073-89942014-12-26doi: 10.3390/sym7010001Min Jung<![CDATA[Robotics, Vol. 4, Pages 1-22: Vision-Based Cooperative Pose Estimation for Localization in Multi-Robot Systems Equipped with RGB-D Cameras]]>
http://www.mdpi.com/2218-6581/4/1/1
We present a new vision based cooperative pose estimation scheme for systems of mobile robots equipped with RGB-D cameras. We first model a multi-robot system as an edge-weighted graph. Then, based on this model, and by using the real-time color and depth data, the robots with shared field-of-views estimate their relative poses in pairwise. The system does not need the existence of a single common view shared by all robots, and it works in 3D scenes without any specific calibration pattern or landmark. The proposed scheme distributes working loads evenly in the system, hence it is scalable and the computing power of the participating robots is efficiently used. The performance and robustness were analyzed both on synthetic and experimental data in different environments over a range of system configurations with varying number of robots and poses.Robotics2014-12-2641Article10.3390/robotics40100011222218-65812014-12-26doi: 10.3390/robotics4010001Xiaoqin WangY. ŞekercioğluTom Drummond<![CDATA[Axioms, Vol. 4, Pages 1-29: Positive-Operator Valued Measure (POVM) Quantization]]>
http://www.mdpi.com/2075-1680/4/1/1
We present a general formalism for giving a measure space paired with a separable Hilbert space a quantum version based on a normalized positive operator-valued measure. The latter are built from families of density operators labeled by points of the measure space. We especially focus on various probabilistic aspects of these constructions. Simple ormore elaborate examples illustrate the procedure: circle, two-sphere, plane and half-plane. Links with Positive-Operator Valued Measure (POVM) quantum measurement and quantum statistical inference are sketched.Axioms2014-12-2541Article10.3390/axioms40100011292075-16802014-12-25doi: 10.3390/axioms4010001Jean GazeauBarbara Heller<![CDATA[Systems, Vol. 3, Pages 1-3: Special Issue on Second Generation General System Theory]]>
http://www.mdpi.com/2079-8954/3/1/1
The aim of this editorial is to briefly introduce some papers of different nature presented by the contributors to the special issue on “Second Generation General System Theory”. These contributions have been focused on the need for building a post-Bertalanffy Systemics, based on new problems, representations, and approaches to complexity. Furthermore, such new Systemics is expected to be able to theoretically generalize new related systemic concepts and approaches introduced by different disciplines. Such a theoretical generalization is going to coincide with a new kind of interdisciplinarity. The latter should substitute the classical one, based on considering problems and solutions within a discipline as equivalent to problems and solutions within another one. This equivalence was used within the framework of general systemic concepts like Anticipation, Completeness, Feedback, Finality, Forecast, Separability, Openness, and Reversibility. The contributions contained in this special issue constitute very interesting examples of new approaches and of their possibilities of theoretical generalization. Therefore, the issue itself can be considered as a window on the new Systemics and its challenges.Systems2014-12-2331Editorial10.3390/systems3010001132079-89542014-12-23doi: 10.3390/systems3010001Gianfranco MinatiEliano Pessa<![CDATA[Econometrics, Vol. 2, Pages 217-249: The Biggest Myth in Spatial Econometrics]]>
http://www.mdpi.com/2225-1146/2/4/217
There is near universal agreement that estimates and inferences from spatial regression models are sensitive to particular specifications used for the spatial weight structure in these models. We find little theoretical basis for this commonly held belief, if estimates and inferences are based on the true partial derivatives for a well-specified spatial regression model. We conclude that this myth may have arisen from past applied work that incorrectly interpreted the model coefficients as if they were partial derivatives, or from use of misspecified models.Econometrics2014-12-2324Article10.3390/econometrics20402172172492225-11462014-12-23doi: 10.3390/econometrics2040217James LeSageR. Pace<![CDATA[IJGI, Vol. 3, Pages 1491-1511: Predicting Relevant Change in High Resolution Satellite Imagery]]>
http://www.mdpi.com/2220-9964/3/4/1491
With the ever increasing volume of remote sensing imagery collected by satellite constellations and aerial platforms, the use of automated techniques for change detection has grown in importance, such that changes in features can be quickly identified. However, the amount of data collected surpasses the capacity of imagery analysts. In order to improve the effectiveness and efficiency of imagery analysts performing data maintenance activities, we propose a method to predict relevant changes in high resolution satellite imagery based on human annotations on selected regions of an image. We study a variety of classifiers in order to determine which is most accurate. Additionally, we experiment with a variety of ways in which a diverse set of training data can be constructed to improve the quality of predictions. The proposed method aids in the analysis of change detection results by using various classifiers to develop a relevant change model that can be used to predict the likelihood of other analyzed areas containing a relevant change or not. These predictions of relevant change are useful to analysts, because they speed the interrogation of automated change detection results by leveraging their observations of areas already analyzed. A comparison of four classifiers shows that the random forest technique slightly outperforms other approaches.ISPRS International Journal of Geo-Information2014-12-2234Article10.3390/ijgi3041491149115112220-99642014-12-22doi: 10.3390/ijgi3041491Matthew Klaric<![CDATA[Econometrics, Vol. 2, Pages 203-216: Testing for A Set of Linear Restrictions in VARMA Models Using Autoregressive Metric: An Application to Granger Causality Test]]>
http://www.mdpi.com/2225-1146/2/4/203
In this paper we propose a test for a set of linear restrictions in a Vector Autoregressive Moving Average (VARMA) model. This test is based on the autoregressive metric, a notion of distance between two univariate ARMA models, M0 and M1, introduced by Piccolo in 1990. In particular, we show that this set of linear restrictions is equivalent to a null distance d(M0,M1 ) between two given ARMA models. This result provides the logical basis for using d(M0,M1) = 0 as a null hypothesis in our test. Some Monte Carlo evidence about the finite sample behavior of our testing procedure is provided and two empirical examples are presented.Econometrics2014-12-2224Article10.3390/econometrics20402032032162225-11462014-12-22doi: 10.3390/econometrics2040203Francesca Di IorioUmberto Triacca<![CDATA[Electronics, Vol. 3, Pages 689-711: A Validated Analytical Model for Availability Prediction of IPTV Services in VANETs]]>
http://www.mdpi.com/2079-9292/3/4/689
In vehicular ad hoc networks (VANETs), besides the original applications typically related to traffic safety, we nowadays can observe an increasing trend toward infotainment applications, such as IPTV services. Quality of experience (QoE), as observed by the end users of IPTV, is highly important to guarantee adequate user acceptance for the service. In IPTV, QoE is mainly determined by the availability of TV channels for the users. This paper presents an efficient and rather generally applicable analytical model that allows one to predict the blocking probability of TV channels, both for channel-switching-induced, as well as for handover-induced blocking events. We present the successful validation of the model by means of simulation, and we introduce a new measure for QoE. Numerous case studies illustrate how the analytical model and our new QoE measure can be applied successfully for the dimensioning of IPTV systems, taking into account the QoE requirements of the IPTV service users in strongly diverse traffic scenarios.Electronics2014-12-1934Article10.3390/electronics30406896897112079-92922014-12-19doi: 10.3390/electronics3040689Bernd WolfingerArian HübnerSadaf Momeni<![CDATA[IJGI, Vol. 3, Pages 1445-1490: A Software Reference Architecture for Service-Oriented 3D Geovisualization Systems]]>
http://www.mdpi.com/2220-9964/3/4/1445
Modern 3D geovisualization systems (3DGeoVSs) are complex and evolving systems that are required to be adaptable and leverage distributed resources, including massive geodata. This article focuses on 3DGeoVSs built based on the principles of service-oriented architectures, standards and image-based representations (SSI) to address practically relevant challenges and potentials. Such systems facilitate resource sharing and agile and efficient system construction and change in an interoperable manner, while exploiting images as efficient, decoupled and interoperable representations. The software architecture of a 3DGeoVS and its underlying visualization model have strong effects on the system’s quality attributes and support various system life cycle activities. This article contributes a software reference architecture (SRA) for 3DGeoVSs based on SSI that can be used to design, describe and analyze concrete software architectures with the intended primary benefit of an increase in effectiveness and efficiency in such activities. The SRA integrates existing, proven technology and novel contributions in a unique manner. As the foundation for the SRA, we propose the generalized visualization pipeline model that generalizes and overcomes expressiveness limitations of the prevalent visualization pipeline model. To facilitate exploiting image-based representations (IReps), the SRA integrates approaches for the representation, provisioning and styling of and interaction with IReps. Five applications of the SRA provide proofs of concept for the general applicability and utility of the SRA. A qualitative evaluation indicates the overall suitability of the SRA, its applications and the general approach of building 3DGeoVSs based on SSI.ISPRS International Journal of Geo-Information2014-12-1934Article10.3390/ijgi3041445144514902220-99642014-12-19doi: 10.3390/ijgi3041445Dieter Hildebrandt<![CDATA[Mathematics, Vol. 2, Pages 232-239: A Conjecture of Han on 3-Cores and Modular Forms]]>
http://www.mdpi.com/2227-7390/2/4/232
In his study of Nekrasov–Okounkov type formulas on “partition theoretic” expressions for families of infinite products, Han discovered seemingly unrelated q-series that are supported on precisely the same terms as these infinite products. In collaboration with Ono, Han proved one instance of this occurrence that exhibited a relation between the numbers a(n) that are given in terms of hook lengths of partitions, with the numbers b(n) that equal the number of 3-core partitions of n. Recently Han revisited the q-series with coefficients a(n) and b(n), and numerically found a third q-series whose coefficients appear to be supported on the same terms. Here we prove Han’s conjecture about this third series by proving a general theorem about this phenomenon.Mathematics2014-12-1924Article10.3390/math20402322322392227-73902014-12-19doi: 10.3390/math2040232Amanda Clemm<![CDATA[Technologies, Vol. 2, Pages 164-165: Special Issue on “Medical Imaging and Image Processing”]]>
http://www.mdpi.com/2227-7080/2/4/164
Over the last decade, Medical Imaging has become an essential component in many fields of bio-medical research and clinical practice. Biologists study cells and generate 3D confocal microscopy data sets, virologists generate 3D reconstructions of viruses from micrographs, radiologists identify and quantify tumors from MRI and CT scans, and neuroscientists detect regional metabolic brain activity from PET and functional MRI scans. On the other hand, Image Processing includes the analysis, enhancement, and display of images captured via various medical imaging technologies. Image reconstruction and modeling techniques allow instant processing of 2D signals to create 3D images. In addition, image processing and analysis can be used to determine the diameter, volume, and vasculature of a tumor or organ, flow parameters of blood or other fluids, and microscopic changes that have not previously been discernible.[...]Technologies2014-12-1924Editorial10.3390/technologies20401641641652227-70802014-12-19doi: 10.3390/technologies2040164Yudong ZhangZhengchao Dong<![CDATA[IJGI, Vol. 3, Pages 1412-1444: Urban Morphological Change Analysis of Dhaka City, Bangladesh, Using Space Syntax]]>
http://www.mdpi.com/2220-9964/3/4/1412
This article is based on a study of the morphological changes of Dhaka City, the capital of Bangladesh. The main objective of the research is to study the transformation of urban morphology in Dhaka City from 1947 to 2007. Three sample wards (18, 19 and 72) of Dhaka City Corporation are strategically selected as the study areas. Ward 72 has an indigenous type of organic settlement, whereas ward 19 is a planned area, and ward 18 represents a mixed (both planned and informal) type of settlement. In this research, the transformation of urban settlement pattern is examined through space syntax. The results show that the organic settlements (ward 72) are highly integrated both in terms of the local and global syntactic measures (lowest standard deviation for local and global integration, with the highest intelligibility values), and are more connectivity. The scenario is opposite in the case of planned settlements. The characteristics of mixed areas (ward 18) lie in between the organic and planned settlements. Therefore, in summary, it can be stated that the integration, connectivity and intelligibility measures of Dhaka City are found to be high, medium and low for the indigenous, mixed and planned settlement types; respectively.ISPRS International Journal of Geo-Information2014-12-1834Article10.3390/ijgi3041412141214442220-99642014-12-18doi: 10.3390/ijgi3041412Bayes AhmedRakibul HasanK. M. Maniruzzaman<![CDATA[Computation, Vol. 2, Pages 246-257: SBMLSimulator: A Java Tool for Model Simulation and Parameter Estimation in Systems Biology]]>
http://www.mdpi.com/2079-3197/2/4/246
The identification of suitable model parameters for biochemical reactions has been recognized as a quite difficult endeavor. Parameter values from literature or experiments can often not directly be combined in complex reaction systems. Nature-inspired optimization techniques can find appropriate sets of parameters that calibrate a model to experimentally obtained time series data. We present SBMLsimulator, a tool that combines the Systems Biology Simulation Core Library for dynamic simulation of biochemical models with the heuristic optimization framework EvA2. SBMLsimulator provides an intuitive graphical user interface with various options as well as a fully-featured command-line interface for large-scale and script-based model simulation and calibration. In a parameter estimation study based on a published model and artificial data we demonstrate the capability of SBMLsimulator to identify parameters. SBMLsimulator is useful for both, the interactive simulation and exploration of the parameter space and for the large-scale model calibration and estimation of uncertain parameter values.Computation2014-12-1824Article10.3390/computation20402462462572079-31972014-12-18doi: 10.3390/computation2040246Alexander DörrRoland KellerAndreas ZellAndreas Dräger<![CDATA[Algorithms, Vol. 7, Pages 685-702: Fusion of Multiple Pyroelectric Characteristics for Human Body Identification]]>
http://www.mdpi.com/1999-4893/7/4/685
Due to instability and poor identification ability of single pyroelectric infrared (PIR) detector for human target identification, this paper proposes a new approach to fuse the information collected from multiple PIR sensors for human identification. Firstly, Fast Fourier Transform (FFT), Short Time Fourier Transform (STFT), Wavelet Transform (WT) and Wavelet Packet Transform (WPT) are adopted to extract features of the human body, which can be achieved by single PIR sensor. Then, we apply Principal Component Analysis (PCA) and Support Vector Machine (SVM) to reduce the characteristic dimensions and to classify the human targets, respectively. Finally, Fuzzy Comprehensive Evaluation (FCE) is utilized to fuse recognition results from multiple PIR sensors to finalize human identification. The pyroelectric characteristics under scenarios with different people and/or different paths are analyzed by various experiments, and the recognition results with/without fusion procedure are also shown and compared. The experimental results demonstrate our scheme has improved efficiency for human identification.Algorithms2014-12-1874Article10.3390/a70406856857021999-48932014-12-18doi: 10.3390/a7040685Wanchun ZhouJi XiongFangmin LiNa JiangNing Zhao<![CDATA[Economies, Vol. 2, Pages 218-219: Urban Economy]]>
http://www.mdpi.com/2227-7099/2/4/218
In a call for papers, for the special issue to be devoted to “Urban Economy” late in 2015, that the Economies editors issued recently, I noted the increased attention that has been given to urban economies during the past quarter century. This is concomitant with the increased importance and role in policy that cities have attained. This is, in part, due to the diminished capacity of national and sub-national governments to find the funds needed for urban projects and services, and in part to the understanding that cities are the key to the economies and societies of most if not all nations.[...]Economies2014-12-1724Editorial10.3390/economies20402182182192227-70992014-12-17doi: 10.3390/economies2040218Peter Kresl<![CDATA[Informatics, Vol. 1, Pages 190-195: Thinking about The Information Age]]>
http://www.mdpi.com/2227-9709/1/3/190
In late October 2014, a new exhibition opened at The Science Museum in London. Titled “The Information Age: Six Networks That Changed Our World” [1], the exhibition received widespread publicity when it was opened by Queen Elizabeth who used this as the opportunity to send her first tweet, using the account @BritishMonarchy.[...]Informatics2014-12-1613Editorial10.3390/informatics10301901901952227-97092014-12-16doi: 10.3390/informatics1030190Antony Bryant<![CDATA[Symmetry, Vol. 6, Pages 1037-1057: Coulomb Solutions from Improper Pseudo-Unitary Free Gauge Field Operator Translations]]>
http://www.mdpi.com/2073-8994/6/4/1037
Fundamental problems of quantum field theory related to the representation problem of canonical commutation relations are discussed within a gauge field version of a van Hove-type model. The Coulomb field generated by a static charge distribution is described as a formal superposition of time-like pseudo-photons in Fock space with a Krein structure. In this context, a generalization of operator gauge transformations is introduced to generate coherent states of Abelian gauge fields interacting with a charged background.Symmetry2014-12-1564Article10.3390/sym6041037103710572073-89942014-12-15doi: 10.3390/sym6041037Andreas Aste<![CDATA[Symmetry, Vol. 6, Pages 1026-1036: Benjamin–Bona–Mahony Equation with Variable Coefficients: Conservation Laws]]>
http://www.mdpi.com/2073-8994/6/4/1026
This paper aims to construct conservation laws for a Benjamin–Bona–Mahony equation with variable coefficients, which is a third-order partial differential equation. This equation does not have a Lagrangian and so we transform it to a fourth-order partial differential equation, which has a Lagrangian. The Noether approach is then employed to construct the conservation laws. It so happens that the derived conserved quantities fail to satisfy the divergence criterion and so one needs to make adjustments to the derived conserved quantities in order to satisfy the divergence condition. The conservation laws are then expressed in the original variable. Finally, a conservation law is used to obtain exact solution of a special case of the Benjamin–Bona–Mahony equation.Symmetry2014-12-1564Article10.3390/sym6041026102610362073-89942014-12-15doi: 10.3390/sym6041026Ben MuatjetjejaChaudry Khalique<![CDATA[Algorithms, Vol. 7, Pages 663-684: COOBBO: A Novel Opposition-Based Soft Computing Algorithm for TSP Problems]]>
http://www.mdpi.com/1999-4893/7/4/663
In this paper, we propose a novel definition of opposite path. Its core feature is that the sequence of candidate paths and the distances between adjacent nodes in the tour are considered simultaneously. In a sense, the candidate path and its corresponding opposite path have the same (or similar at least) distance to the optimal path in the current population. Based on an accepted framework for employing opposition-based learning, Oppositional Biogeography-Based Optimization using the Current Optimum, called COOBBO algorithm, is introduced to solve traveling salesman problems. We demonstrate its performance on eight benchmark problems and compare it with other optimization algorithms. Simulation results illustrate that the excellent performance of our proposed algorithm is attributed to the distinct definition of opposite path. In addition, its great strength lies in exploitation for enhancing the solution accuracy, not exploration for improving the population diversity. Finally, by comparing different version of COOBBO, another conclusion is that each successful opposition-based soft computing algorithm needs to adjust and remain a good balance between backward adjacent node and forward adjacent node.Algorithms2014-12-1274Article10.3390/a70406636636841999-48932014-12-12doi: 10.3390/a7040663Qingzheng XuLemeng GuoNa WangYongjian He<![CDATA[Symmetry, Vol. 6, Pages 1011-1025: Privacy-Enhancing Security Protocol in LTE Initial Attack]]>
http://www.mdpi.com/2073-8994/6/4/1011
Long-Term Evolution (LTE) is a fourth-generation mobile communication technology implemented throughout the world. It is the communication means of smartphones that send and receive all of the private date of individuals. M2M, IOT, etc., are the base technologies of mobile communication that will be used in the future cyber world. However, identification parameters, such as International Mobile Subscriber Identity (IMSI), Radio Network Temporary Identities (RNTI), etc., in the initial attach section for accessing the LTE network are presented with the vulnerability of being exposed as clear text. Such vulnerability does not end in a mere identification parameter, but can lead to a secondary attack using the identification parameter, such as replication of the smartphone, illegal use of the mobile communication network, etc. This paper proposes a security protocol to safely transmit identification parameters in different cases of the initial attach. The proposed security protocol solves the exposed vulnerability by encrypting the parameters in transmission. Using an OPNET simulator, it is shown that the average rate of delay and processing ratio are efficient in comparison to the existing process.Symmetry2014-12-1264Article10.3390/sym6041011101110252073-89942014-12-12doi: 10.3390/sym6041011Uijin JangHyungmin LimHyungjoo Kim<![CDATA[IJGI, Vol. 3, Pages 1387-1411: Targeting: Logistic Regression, Special Cases and Extensions]]>
http://www.mdpi.com/2220-9964/3/4/1387
Logistic regression is a classical linear model for logit-transformed conditional probabilities of a binary target variable. It recovers the true conditional probabilities if the joint distribution of predictors and the target is of log-linear form. Weights-of-evidence is an ordinary logistic regression with parameters equal to the differences of the weights of evidence if all predictor variables are discrete and conditionally independent given the target variable. The hypothesis of conditional independence can be tested in terms of log-linear models. If the assumption of conditional independence is violated, the application of weights-of-evidence does not only corrupt the predicted conditional probabilities, but also their rank transform. Logistic regression models, including the interaction terms, can account for the lack of conditional independence, appropriate interaction terms compensate exactly for violations of conditional independence. Multilayer artificial neural nets may be seen as nested regression-like models, with some sigmoidal activation function. Most often, the logistic function is used as the activation function. If the net topology, i.e., its control, is sufficiently versatile to mimic interaction terms, artificial neural nets are able to account for violations of conditional independence and yield very similar results. Weights-of-evidence cannot reasonably include interaction terms; subsequent modifications of the weights, as often suggested, cannot emulate the effect of interaction terms.ISPRS International Journal of Geo-Information2014-12-1134Article10.3390/ijgi3041387138714112220-99642014-12-11doi: 10.3390/ijgi3041387Helmut Schaeben<![CDATA[Robotics, Vol. 3, Pages 400-416: Drive the Drive: From Discrete Motion Plans to Smooth Drivable Trajectories]]>
http://www.mdpi.com/2218-6581/3/4/400
Autonomous navigation in real-world industrial environments is a challenging task in many respects. One of the key open challenges is fast planning and execution of trajectories to reach arbitrary target positions and orientations with high accuracy and precision, while taking into account non-holonomic vehicle constraints. In recent years, lattice-based motion planners have been successfully used to generate kinematically and kinodynamically feasible motions for non-holonomic vehicles. However, the discretized nature of these algorithms induces discontinuities in both state and control space of the obtained trajectories, resulting in a mismatch between the achieved and the target end pose of the vehicle. As endpose accuracy is critical for the successful loading and unloading of cargo in typical industrial applications, automatically planned paths have not been widely adopted in commercial AGV systems. The main contribution of this paper is a path smoothing approach, which builds on the output of a lattice-based motion planner to generate smooth drivable trajectories for non-holonomic industrial vehicles. The proposed approach is evaluated in several industrially relevant scenarios and found to be both fast (less than 2 s per vehicle trajectory) and accurate (end-point pose errors below 0.01 m in translation and 0.005 radians in orientation).Robotics2014-12-1134Article10.3390/robotics30404004004162218-65812014-12-11doi: 10.3390/robotics3040400Henrik AndreassonJari SaarinenMarcello CirilloTodor StoyanovAchim Lilienthal<![CDATA[Future Internet, Vol. 6, Pages 773-799: Inside Technology: Opening the Black Box of Health-Website Configuration and Content Management]]>
http://www.mdpi.com/1999-5903/6/4/773
Given the existing divide related to Internet skills and types of Internet use, it is safe to assume that a large proportion of the population uses the Internet for health purposes in a partially productive fashion. We suggest that in addition to user characteristics, another factor that inhibits productive Internet use, and thus contributes to the existing gap, is related to the ways in which the technology is configured. The goal of this study was to explore the processes that webmasters and content managers use for constructing and producing, or selecting content, for health websites. Interviews conducted with 23 website builders and managers of websites that represent public and non-public health organizations revealed that they do not plan or conduct activities for content needs elicitation, either in the design stage or on an ongoing basis. Rather, these professionals rely on a “self-embodiment” standard, whereby their and their cohorts’ expectations determine the quality and functionality of the websites’ structure and content. Hence, target groups beyond their social sphere are disregarded, and instead of new opportunities, new cleavages are created. We recommended that government, public and non-public stakeholders work to establish construction standards, to ensure that health websites meet the needs of varied end-user populations.Future Internet2014-12-1064Article10.3390/fi60407737737991999-59032014-12-10doi: 10.3390/fi6040773Esther BraininEfrat Neter<![CDATA[Electronics, Vol. 3, Pages 675-688: Kronecker-Based Fusion Rule for Cooperative Spectrum Sensingwith Multi-Antenna Receivers]]>
http://www.mdpi.com/2079-9292/3/4/675
This paper considers a novel fusion rule for spectrum sensing scheme for a cognitive radio network with multi-antenna receivers. The proposed scheme exploits the fact that when any primary signal is present, measurements are spatially correlated due to presence of inter-antenna and inter-receiver spatial correlation. In order to exploit this spatial structure, the generalized likelihood ratio test (GLRT) operates with the determinant of the sample covariance matrix. Therefore, it depends on the sample size N and the dimensionality of the received data (i.e., the number of receivers K and antennas L). However, when the dimensionality fK; Lg is on the order, or larger than the sample size N, the GLRT degenerates due to the ill-conditioning of the sample covariance matrix. In order to circumvent this issue, we propose two techniques that exploit the inner spatial structure of the received observations by using single pair and multi-pairs Kronecker products. The performance of the proposed detectors is evaluated by means of numerical simulations, showing important advantages with respect to the traditional (i.e., unstructured) GLRT approach.Electronics2014-12-1034Article10.3390/electronics30406756756882079-92922014-12-10doi: 10.3390/electronics3040675Sadiq AliMagnus JanssonGonzalo Seco-GranadosJosé López-Salcedo<![CDATA[Electronics, Vol. 3, Pages 661-674: Optimizing Power Heterogeneous Functional Units for Dynamic and Static Power Reduction]]>
http://www.mdpi.com/2079-9292/3/4/661
Power consumption is the major constraint for modern microprocessor designs. In particular, static power consumption becomes a serious problem as the transistor size shrinks via semiconductor technology improvement. This paper proposes a technique that reduces the static power consumed by functional units. It exploits the activity rate of functional units and utilizes the power heterogeneous functional units. From detailed simulations, we investigate the conditions in which the proposed technique works effectively for simultaneous dynamic and static power reduction and find that we can reduce the total power by 11.2% if two out of four leaky functional units are replaced by leakless ones in the situation where the static power occupies half of the total power.Electronics2014-12-1034Article10.3390/electronics30406616616742079-92922014-12-10doi: 10.3390/electronics3040661Toshinori SatoYoshimi Shibata<![CDATA[IJGI, Vol. 3, Pages 1372-1386: Use of the NASA Giovanni Data System for Geospatial Public Health Research: Example of Weather-Influenza Connection]]>
http://www.mdpi.com/2220-9964/3/4/1372
The NASA Giovanni data analysis system has been recognized as a useful tool to access and analyze many different types of remote sensing data. The variety of environmental data types has allowed the use of Giovanni for different application areas, such as agriculture, hydrology, and air quality research. The use of Giovanni for researching connections between public health issues and Earth’s environment and climate, potentially exacerbated by anthropogenic influence, has been increasingly demonstrated. In this communication, the pertinence of several different data parameters to public health will be described. This communication also provides a case study of the use of remote sensing data from Giovanni in assessing the associations between seasonal influenza and meteorological parameters. In this study, logistic regression was employed with precipitation, temperature and specific humidity as predictors. Specific humidity was found to be associated (p &lt; 0.05) with influenza activity in both temperate and tropical climate. In the two temperate locations studied, specific humidity was negatively correlated with influenza; conversely, in the three tropical locations, specific humidity was positively correlated with influenza. Influenza prediction using the regression models showed good agreement with the observed data (correlation coefficient of 0.5–0.83).ISPRS International Journal of Geo-Information2014-12-1034Communication10.3390/ijgi3041372137213862220-99642014-12-10doi: 10.3390/ijgi3041372James AckerRadina SoebiyantoRichard KiangSteve Kempler<![CDATA[IJGI, Vol. 3, Pages 1352-1371: Mapping Entomological Dengue Risk Levels in Martinique Using High-Resolution Remote-Sensing Environmental Data]]>
http://www.mdpi.com/2220-9964/3/4/1352
Controlling dengue virus transmission mainly involves integrated vector management. Risk maps at appropriate scales can provide valuable information for assessing entomological risk levels. Here, results from a spatio-temporal model of dwellings potentially harboring Aedes aegypti larvae from 2009 to 2011 in Tartane (Martinique, French Antilles) using high spatial resolution remote-sensing environmental data and field entomological and meteorological information are presented. This tele-epidemiology methodology allows monitoring the dynamics of diseases closely related to weather/climate and environment variability. A Geoeye-1 image was processed to extract landscape elements that could surrogate societal or biological information related to the life cycle of Aedes vectors. These elements were subsequently included into statistical models with random effect. Various environmental and meteorological conditions have indeed been identified as risk/protective factors for the presence of Aedes aegypti immature stages in dwellings at a given date. These conditions were used to produce dynamic high spatio-temporal resolution maps from the presence of most containers harboring larvae. The produced risk maps are examples of modeled entomological maps at the housing level with daily temporal resolution. This finding is an important contribution to the development of targeted operational control systems for dengue and other vector-borne diseases, such as chikungunya, which is also present in Martinique.ISPRS International Journal of Geo-Information2014-12-1034Article10.3390/ijgi3041352135213712220-99642014-12-10doi: 10.3390/ijgi3041352Vanessa MachaultAndré YébakimaManuel EtienneCécile VignollesPhilippe PalanyYves TourreMarine GuérécheauJean-Pierre Lacaux<![CDATA[Robotics, Vol. 3, Pages 371-399: The Role of Visibility in Pursuit/Evasion Games]]>
http://www.mdpi.com/2218-6581/3/4/371
The cops-and-robber (CR) game has been used in mobile robotics as a discretized model (played on a graph G) of pursuit/evasion problems. The “classic” CR version is a perfect information game: the cops’ (pursuer’s) location is always known to the robber (evader) and vice versa. Many variants of the classic game can be defined: the robber can be invisible and also the robber can be either adversarial (tries to avoid capture) or drunk (performs a random walk). Furthermore, the cops and robber can reside in either nodes or edges of G. Several of these variants are relevant as models or robotic pursuit/evasion. In this paper, we first define carefully several of the variants mentioned above and related quantities such as the cop number and the capture time. Then we introduce and study the cost of visibility (COV), a quantitative measure of the increase in difficulty (from the cops’ point of view) when the robber is invisible. In addition to our theoretical results, we present algorithms which can be used to compute capture times and COV of graphs which are analytically intractable. Finally, we present the results of applying these algorithms to the numerical computation of COV.Robotics2014-12-0834Article10.3390/robotics30403713713992218-65812014-12-08doi: 10.3390/robotics3040371Athanasios KehagiasDieter MitschePaweł Prałat<![CDATA[JSAN, Vol. 3, Pages 297-330: Towards Long-Term Multi-Hop WSN Deployments for Environmental Monitoring: An Experimental Network Evaluation]]>
http://www.mdpi.com/2224-2708/3/4/297
This paper explores the network performance and costs associated with the deployment, labor, and maintenance of a long-term outdoor multi-hop wireless sensor network (WSN) located at the Audubon Society of Western Pennsylvania (ASWP), which has been in operation for more than four years for environmental data collection. The WSN performance is studied over selected time periods during the network deployment time, based on two different TinyOS-based WSN routing protocols: commercial XMesh and the open-source Collection Tree Protocol (CTP). Empirical results show that the network performance is improved with CTP (i.e., 79% packet reception rate, 96% packet success rate and 0.2% duplicate packets), versus using XMesh (i.e., 36% packet reception rate and 46% packet success rate, with 3%–4% duplicate packets). The deployment cost of the 52-node, 253-sensor WSN is $31,500 with an additional $600 per month in labor and maintenance resulting in a cost of $184 m−2·y−1 of sensed area. Network maintenance during the first four years of operation was performed on average every 12 days, costing approximately $187 for each field visit.Journal of Sensor and Actuator Networks2014-12-0534Article10.3390/jsan30402972973302224-27082014-12-05doi: 10.3390/jsan3040297Miguel NavarroTyler DavisGerman VillalbaYimei LiXiaoyang ZhongNewlyn ErrattXu LiangYao Liang<![CDATA[Econometrics, Vol. 2, Pages 169-202: Success at the Summer Olympics: How Much Do Economic Factors Explain?]]>
http://www.mdpi.com/2225-1146/2/4/169
Many econometric analyses have attempted to model medal winnings as dependent on per capita GDP and population size. This approach ignores the size and composition of the team of athletes, especially the role of female participation and the role of sports culture, and also provides an inadequate explanation of the variability between the outcomes of countries with similar features. This paper proposes a model that offers two substantive advancements, both of which shed light on previously hidden aspects of Olympic success. First, we propose a selection model that treats the process of fielding any winner and the subsequent level of total winnings as two separate, but related, processes. Second, our model takes a more structural angle, in that we view GDP and population size as inputs into the “production” of athletes. After that production process, those athletes then compete to win medals. We use country-level panel data for the seven Summer Olympiads from 1988 to 2012. The size and composition of the country’s Olympic team are shown to be highly significant factors, as is also the past performance, which generates a persistence effect.Econometrics2014-12-0524Article10.3390/econometrics20401691692022225-11462014-12-05doi: 10.3390/econometrics2040169Pravin TrivediDavid Zimmer<![CDATA[IJGI, Vol. 3, Pages 1334-1351: The RichWPS Environment for Orchestration]]>
http://www.mdpi.com/2220-9964/3/4/1334
Web service (WS) orchestration can be considered as a fundamental concept in service-oriented architectures (SOA), as well as in spatial data infrastructures (SDI). In recent years in SOA, advanced solutions were developed, such as realizing orchestrated web services on the basis of already existing more fine-granular web services by using standardized notations and existing orchestration engines. Even if the concepts can be mapped to the field of SDI, on a conceptual level the implementations target different goals. As a specialized form of a common web service, an Open Geospatial Consortium (OGC) web service (OWS) is optimized for a specific purpose. On the technological level, web services depend on standards like the Web Service Description Language (WSDL) or the Simple Object Access Protocol (SOAP). However OWS are different. Consequently, a new concept for OWS orchestration is needed that works on the interface provided by OWS. Such a concept is presented in this work. The major component is an orchestration engine integrated in a Web Processing Service (WPS) server that uses a domain specific language (DSL) for workflow description. The developed concept is the base for the realization of new functionality, such as workflow testing, and workflow optimization.ISPRS International Journal of Geo-Information2014-12-0534Article10.3390/ijgi3041334133413512220-99642014-12-05doi: 10.3390/ijgi3041334Felix BensmannDorian Alcacer-LabradorDennis ZiegenhagenRainer Roosmann<![CDATA[IJGI, Vol. 3, Pages 1317-1333: Accuracy and Effort of Interpolation and Sampling: Can GIS Help Lower Field Costs?]]>
http://www.mdpi.com/2220-9964/3/4/1317
Sedimentation is a problem for all reservoirs in the Black Hills of South Dakota. Before working on sediment removal, a survey on the extent and distribution of the sediment is needed. Two sample lakes were used to determine which of three interpolation methods gave the most accurate volume results. A secondary goal was to see if fewer samples could be taken while still providing similar results. The smaller samples would mean less field time and thus lower costs. Subsamples of 50%, 33% and 25% were taken from the total samples and evaluated for the lowest Root Mean Squared Error values. Throughout the trials, the larger sample sizes generally showed better accuracy than smaller samples. Graphing the sediment volume estimates of the full sample, 50%, 33% and 25% showed little improvement after a sample of approximately 40%–50% when comparing the asymptote of the separate samples. When we used smaller subsamples the predicted sediment volumes were normally greater than the full sample volumes. It is suggested that when planning future sediment surveys, workers plan on gathering data at approximately every 5.21 meters. These sample sizes can be cut in half and still retain relative accuracy if time savings are needed. Volume estimates may slightly suffer with these reduced samples sizes, but the field work savings can be of benefit. Results from these surveys are used in prioritization of available funds for reclamation efforts. ISPRS International Journal of Geo-Information2014-12-0534Article10.3390/ijgi3041317131713332220-99642014-12-05doi: 10.3390/ijgi3041317Greg SimpsonYi Wu<![CDATA[IJGI, Vol. 3, Pages 1293-1316: A GIS Approach to Urban History: Rome in the 18th Century]]>
http://www.mdpi.com/2220-9964/3/4/1293
This article explores the integration of GIS technology with urban historical studies, focusing on one case study from the 18th century, the project Historical atlas of the modern Rome. The methodology employed in this project allows for effectiveness and accuracy in historical data acquisition and integration, which enables refined analyses of socioeconomic and environmental phenomena. The approach outlined in this article allowed researchers from different disciplines—city historians, archaeologists, demographists, economists, and so on—to interpret urban phenomenologies according to different thematic keys. These interpretations were derived from archival sources that complement each other and offer diversified insights into the urban context. The techniques described in the article are based on methods of data acquisition and spatial analysis developed in a GIS environment by exploiting the effectiveness of this technology in the quantitative treatment of cartographic and documentary sources.ISPRS International Journal of Geo-Information2014-12-0534Article10.3390/ijgi3041293129313162220-99642014-12-05doi: 10.3390/ijgi3041293Keti Lelo<![CDATA[IJGI, Vol. 3, Pages 1278-1292: A Systems Perspective on Volunteered Geographic Information]]>
http://www.mdpi.com/2220-9964/3/4/1278
Volunteered geographic information (VGI) is geographic information collected by way of crowdsourcing. However, the distinction between VGI as an information product and the processes that create VGI is blurred. Clearly, the environment that influences the creation of VGI is different than the information product itself, yet most literature treats them as one and the same. Thus, this research is motivated by the need to formalize and standardize the systems that support the creation of VGI. To this end, we propose a conceptual framework for VGI systems, the main components of which—project, participants, and technical infrastructure—form an environment conducive to the creation of VGI. Drawing on examples from OpenStreetMap, Ushahidi, and RinkWatch, we illustrate the pragmatic relevance of these components. Applying a system perspective to VGI allows us to better understand the components and functionality needed to effectively create VGI.ISPRS International Journal of Geo-Information2014-12-0434Article10.3390/ijgi3041278127812922220-99642014-12-04doi: 10.3390/ijgi3041278Victoria FastClaus Rinner